[WICKET-6944] Memory leak in WicketEndpoint

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 9.7.0
• Fix Version/s: 10.0.0-M1, 8.14.0, 9.8.0
• Component/s: wicket-native-websocket
• Assignee: Martin Tzvetanov Grigorov
• Reporter: Thomas Heigl
• Created: 10/Jan/22 17:54
• Updated: 22/Mar/22 11:46
• Resolved: 11/Jan/22 12:24

Description

Our application OOMed yesterday after about 2-3 weeks of continuous uptime. We normally deploy every other day, so we never noticed this issue before.

The heap dump identified the possible culprit as WicketEndpoint$ApplicationListener:

Every new websocket connection registers a new instance of this application listener and after a while we ended up with millions of these listeners:

@Override
public void onOpen(Session session, EndpointConfig endpointConfig)
{
    String appName = getApplicationName(session);

    WebApplication app = (WebApplication) WebApplication.get(appName);
    app.getApplicationListeners().add(new ApplicationListener(applicationDestroyed));

    try
    {
        ThreadContext.setApplication(app);
        javaxWebSocketProcessor = new JavaxWebSocketProcessor(session, app, endpointConfig);
    }
    finally
    {
        ThreadContext.detach();
    }
}

Instead of creating a new listener for every connection, the listener should be a singleton.

Issue Links

• is cloned by: WICKET-6965 Memory leak in WicketEndpoint